1. Field of the Invention
This invention relates to dry pressed powder compositions, and in particular, dry pressed powder compositions in a stick-type form containing, for example, an antiperspirant.
2. Prior Art
Current stick-type compositions, for example an antiperspirant, consist of a bacteriostat or other biologically active compound, for example an active antiperspirant such as zirconium or aluminum chlorohydrate, dispersed in a vehicle such as alcohol-based gells, e.g. ethanol, or a glycol such as propylene glycol. In these type of compositions, gelation is effected by the use of a soap, e.g. sodium stearate. The solid stick-type compositions may also contain other ingredients, such as water, humectants, gums, surfactants, dyes, perfumes, etc. These type compositions have drawbacks in that when applied to the skin, they have an undesirable wet feeling. Additionally, ethanol-based compositions are very volatile and will evaporate in the package at room temperature, volatility being further exaggerated at elevated temperatures. As a result of this volatility, the stick shrinks and becomes useless. Such a composition creates packaging problems and has a comparatively short shelf life. Glycol based compositions, on the other hand, do not have these disadvantages, but provide a product which is hard and waxy. As a result, this provides an undesirable feel when applied, has little covering capability and is sticky and wet feeling during and after application. Known vehicles for antiperspirants include volatile silicone in a wax-type base. This type formula has some of the same disadvantages as the previous compositions. Other cosmetic preparations, such as blushers and lipsticks, utilize fats and/or waxes such as beeswax, carnauba wax, candeli wax, microcrystalline wax, vegetable oils, castor oils, and the like. Vehicles of this type can only be used in certain formulations of cosmetic products because of the many technical and formulation problems. Compression of a powder into a stick form has been attempted for an antiperspirant but has not produced a successful product. Attempts to produce such products has resulted in hard sticks that are difficult to apply, e.g. difficult to deposit a sufficient amount of powder to be useful. Attempts have been made to reduce the degree of compression. However, when the degree of compression is reduced, the powder stick crumbles and does not stay in a compressed form. Other attempts to solve these problems have included applying a separate wrapper of a dry film or film form of coating to the stick composition to prevent crumbling or shedding or dusting of the loosely compacted powder, see for example U.S. Pat. No. 3,471,611 to Scott et al. Other attempts include the use of gums or other material that has adhesive binders, see for example U.S. Pat. No. 3,800,034 to Kircher. None of these attempts to produce an improved dry pressed powder composition have been successful.
More specifically, the following U.S. patents are relevant to applicant's invention: U.S. Pat. Nos. 1,968,475 to Beckwith et al; 3,471,611 to Scott et al; 3,800,034 to Kircher; 4,126,679 to Davy et al; 4,226,889 to Yuhas; 4,322,400 to Yuhas; and German Pat. No. 2,852,988.
Kircher et al describes a dry pressed powder stick for makeup composition. The majority of the composition of this pressed powder stick is finely divided chalk, i.e., calcium carbonate. This stick can include such ingredients as magnesium carbonate, zinc oxide, starch and starch derivatives with the use of certain forms of cellulose, such as methyl and ethyl cellulose, as binders. The material, including binders, can be formed into sticks by extrusion and drying of the liquid or by pressing or molding operations. Pressures used in forming the dry pressed product are not indicated. The German Patent shows a powder stick formed by pressure of three and one half to five and one half kilograms per square centimeter. Methyl cellulose is listed as one of the binder materials which can be used. Other contents listed include: magnesium carbonate, zinc oxide and silicon dioxide.
Scott et al shows a compressed powder cosmetic article which uses a fragile film formed of materials which include cellulose of the methyl, ethyl or nitro forms. The film forming materials are deposited on the cosmetic powder after compression into its commercial form.
Beckwith et al shows a powder cosmetic composition which can be formed in a mold, such as a previously used compact container by means of the evaporation of a solvent in air. The powder base may include magnesium carbonate or zinc oxide among other materials.
Davy et al shows the formation of a cosmetic stick such as a deodorant or antiperspirant stick by means of the addition of powdered materials usually astringent salts to a matrix of silicon oil and alcohol. The sticks are formed by pouring the mixture at elevated temperatures into molds and cooling the material.
The Yuhas patents show solid stick-type cosmetic compositions formed from stearates, water, and an "active" material.